The electronics fabrication industry uses chemical precursor containers that convert liquid chemicals into chemical vapor for delivery to electronics fabrication reactors, i.e. tools, for conducting chemical vapor deposition (“CVD”). CVD is a favored technique for forming layers, films and other depositions in the construction of electronic fabrications such as integrated circuits or computer chips. Liquids or solids are preferred as sources of supply because of the efficiency of transport and storage of a volume of chemical precursor, but the industry frequently prefers to actually deliver the chemical precursor at the site of the tool in the form of a vapor, i.e. CVD. Alternatively, some fabrications are conducted using direct liquid injection (“DLI”), although even then, the liquid is vaporized in the tool after delivery.
When using vapor delivery for CVD, the containers typically have an inert carrier gas passed through them or bubbled, i.e., bubbler, to carry entrained chemical precursor vapor in the inert carrier gas to the tool. Bubblers typically have a downtube inlet where the carrier gas is introduced into the container under the surface of the liquid chemical precursor wherein the carrier gas bubbles up through the liquid chemical precursor, entraining the chemical precursor as the carrier gas surfaces the liquid as a bubble and exits the container or bubbler by an outlet set above the liquid level of the chemical precursor.
It is undesirable to have the chemical precursor leave the container through the outlet in the liquid form, even as small droplets. A homogenous vapor is preferred as the dispensed product of such bubblers. This avoids corrosion, cleanup, and uneven flow, especially through mass flow controllers which control the flow of chemical precursor from the bubbler to the tool in a precisely metered fashion.
The industry has attempted various forms of splashguards for bubblers to address this issue, such as in: U.S. Pat. No. 6,520,218; EP 1 329 540; US 2004/0013577; EP 0 420 596; U.S. Pat. No. 5,589,110; U.S. Pat. No. 7,077,388; US 2003/0042630; U.S. Pat. No. 5,776,255; and U.S. Pat. No. 4,450,118. Each of these attempts to provide splashguard function has had less than desired performance, but the present invention as disclosed below successfully provides high levels of splashguard function, while still allowing high flows of chemical precursor or flows under high vacuum or high pressure differential conditions as will be described and illustrated below.